通过电解水制备氢气是实现“碳中和”目标的理想途径之一.因此,可在全p H条件下使用的氢析出(HER)催化剂的研发是近年来电催化领域的研究热点.原子级分散的催化剂,能够在保留铂族金属(PGM)固有活性的同时,降低催化剂中PGM的用量.虽然可...通过电解水制备氢气是实现“碳中和”目标的理想途径之一.因此,可在全p H条件下使用的氢析出(HER)催化剂的研发是近年来电催化领域的研究热点.原子级分散的催化剂,能够在保留铂族金属(PGM)固有活性的同时,降低催化剂中PGM的用量.虽然可以通过X射线吸收光谱(XAS)来表征原子分散的PGM电催化剂的配位环境,但目前对原子空间分布的控制仍然具有挑战.本文制备了钒掺杂钨青铜内通道氨配位的钌单原子催化剂(Ru/V-NHWO),用于全p H范围内的HER反应.采用X射线衍射(XRD)、高角环形暗场扫描透射电镜(HAADF-STEM)、X射线光电子能谱(XPS)和原位X射线吸收光谱(XAS)等进行表征,研究了钌单原子与V-NHWO载体的结合方式以及构效关系,并采用密度泛函理论(DFT)计算探索了催化剂中诸多位点的活性贡献.在1 mol/LKOH, 0.5 mol/L H_(2)SO_(4)和1 mol/L磷酸盐缓冲溶液中,其在10 m Acm^(-2)下的过电位分别为28.0, 29.6和40.6 m V.同时,在过电位100 m V时,质量活性分别达到3930, 1941和602.8 m Amg^(-1)Ru,数倍于同等条件下的商业铂碳.XRD结果表明,钌的引入可以确保催化剂在氩气条件下热解后仍保持六方钨铵青铜晶相,证明钌与钨铵青铜六方晶体通道内氨物种,即“通道氨”的结合.HAADF-STEM结果表明,钌原子与NHWO间存在强烈相互作用,有助于提升HER性能.XPS和XAS结果表明, W5+信号出现在引入钌后,峰位置的结合能增加且峰面积降低,说明钌与通道氨之间存在相互作用.N的XPS结果表明,钌的引入导致了金属氨键的形成.XAS结果表明, Ru/V-NHWO/CC中钌单原子和钌团簇共存,钌单原子与通道氨配位,并且钒的引入会诱发V-NHWO中金属键长缩短,这表明催化剂的金属性得到了提升,有利于改善其导电性.采用DFT计算进一步研究了HER活性的来源.相比于V-NHWO载体和钌团簇修饰的V-NHWO,以单原子形式结合的钌具有更低的水解离能垒,该能垒在氨桥接的钌双原子垂直插入、钒掺杂和多通道插入等多种因素作用下进一步降低.同时,氢中间体结合能得到了相应的优化而趋近于0 e V.此外,差分电荷密度模拟结果表明,氢中间体结合后, V-NHWO对于钌单原子存在明显的供电子行为,有利于HER动力学过程.综上,本工作报道了金属载体对于高分散金属原子空间分布调控的重要作用,可为设计和构筑可应用于诸多能源转换过程的新型原子级分散催化剂提供参考.展开更多
Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conv...Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conversion.However,high-performance TiO_(2)-based electrocatalysts for HER are quite limited,and the cat alytic active centers still remain elusive.Herein,a simple strategy is demonstrated for the synthesis of TiO_(2)-carbon composite(TiO_(2)/C)with high HER performance and stability.The remarkable HER performance of TiO_(2)/C can be ascribed to the doping of carbon atoms,which leads to stronger hybridization of Ti 3d and O 2p orbitals,thus substantially improving the electrocatalytic efficiency.This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electro catalysts with high catalytic activity and stability at high current density for HER.展开更多
As a choke point in water electrolysis,the oxygen evolution reaction(OER)suffers from the severe electrode polarization and large overpotential.Herein,the porous hierarchical hetero-(Nis Fe)FeN/Ni catalysts are in sit...As a choke point in water electrolysis,the oxygen evolution reaction(OER)suffers from the severe electrode polarization and large overpotential.Herein,the porous hierarchical hetero-(Nis Fe)FeN/Ni catalysts are in situ constructed for the eficient electrocatalytic OER.X-ray absorption fine structure characterizations reveal the strong Ni-Fe bimetallic interaction in(Niz Fex)FeN/Ni.Theoretical study indicates the heterojunction and bimetallic interaction decrease the free-energy change for the rate-limiting step of the OER and the overpotential thereof.In addition,the high conductivity and porous hierarchical morphology favor the electron transfer,electrolyte access and O2 release.Consequently,the optimized catalyst achieves a low overpotential of 223 mV at 10 mA.cm^-2,a small Tafel slope of 68 mV:dec^-1,and a high stability.The excellent performance of the optimized catalyst is also demonstrated by the overall water electrolysis with a low working voltage and high Faradaic efficiency.Moreover,the correlation between the structure and performance is well established by the experimental characterizations and theoretical calculations,which confirms the origin of the OER activity from the surface metal oxyhydroxide in situ generated upon applying the current.This study suggests a promising approach to the advanced OER electrocatalysts for practical applications by constructing the porous hierarchical metal-compound/metal heterojunctions.展开更多
The structural flexibility of hybrid perovskite materials allows for phase transition and consequently thermochromic properties.Here we investigate the thermochromic performance in a series of copper-based layered per...The structural flexibility of hybrid perovskite materials allows for phase transition and consequently thermochromic properties.Here we investigate the thermochromic performance in a series of copper-based layered perovskites with organic cations having different alky chain lengths. Their transition temperature is found to be dependent on the organic cations due to molecular motion and hydrogen bond interaction, providing possibilities to prepare thermochromic semiconductors near room temperature for smart window applications.展开更多
Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,includ...Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,including a H_(2)O_(2)molecule dissociated on the metal single site to form the(metal_(1)-N_(x))=O active site,and followed by the dissociation of another H_(2)O_(2)on the other side of metal atom to form O=(metal_(1)-N_(x))=O intermediate center,which is active for the adsorption of benzene molecule via the formation of a C-O bond to form phenol.In this manuscript,we report a Cu SAC with nitrogen and oxygen dual-coordination(Cu1-N3O1 moiety)that doesn’t need the first H_(2)O_(2)activation process,as verified by both experimental and density function theory(DFT)calculations results.Compared with the counterpart nitrogen-coordinated Cu SAC(denoted as Cu1/NC),Cu SAC with nitrogen and oxygen dual-coordination(denoted as Cu1/NOC)exhibits 2.5 times higher turnover frequency(TOF)and 1.6 times higher utilization efficiency of H_(2)O_(2).Particularly,the coordination number(CN)of Cu atom in Cu1/NOC maintains four even after H_(2)O_(2)treatment and reaction.Combining DFT calculations,the dynamic evolution of single atomic Cu with nitrogen and oxygen dualcoordination in hydroxylation of benzene is proposed.These findings provide an efficient route to improve the catalytic performance through regulating the coordination environments of SACs and demonstrate a new reaction mechanism in hydroxylation of benzene to phenol reaction.展开更多
The investigation of earth-abundant electrocatalysts for efficient water electrolysis is of central importance in renewable energy system, which is currently impeded by the large overpotential of oxygen evolution reac...The investigation of earth-abundant electrocatalysts for efficient water electrolysis is of central importance in renewable energy system, which is currently impeded by the large overpotential of oxygen evolution reaction (OER). NiFe sulfides show promising OER activity but are troubled by their low intrinsic conductivities. Herein, we demonstrate the construction of the porous core-shell heterojunctions of FeNi3@(Fe,Ni)S_(2) with tunable shell thickness via the reduction of hierarchical NiFe(OH)x nanosheets followed by a partial sulfidization. The conductive FeNi3 core provides the highway for electron transport, and the (Fe,Ni)S_(2) shell offers the exposed surface for in situ generation of S-doped NiFe-oxyhydroxides with high intrinsic OER activity, which is supported by the combined experimental and theoretical studies. In addition, the porous hierarchical morphology favors the electrolyte access and O_(2) liberation. Consequently, the optimized catalyst achieves an excellent OER performance with a low overpotential of 288 mV at 100 mA·cm^(−2), a small Tafel slope of 48 mV·dec^(−1), and a high OER durability for at least 1,200 h at 200 mA·cm^(−2). This study provides an effective way to explore the advanced earth-abundant OER electrocatalysts by constructing the heterojunctions between metal and corresponding metal-compounds via the convenient post treatment, such as nitridation and sulfidization.展开更多
Surface enhanced Raman scattering(SERS)is a rapid and nondestructive technique that is capable of detecting and identifying chemical or biological compounds.Sensitive SERS quantification is vital for practical applica...Surface enhanced Raman scattering(SERS)is a rapid and nondestructive technique that is capable of detecting and identifying chemical or biological compounds.Sensitive SERS quantification is vital for practical applications,particularly for portable detection of biomolecules such as amino acids and nucleotides.However,few approaches can achieve sensitive and quantitative Raman detection of these most fundamental components in biology.Herein,a noblemetal-free single-atom site on a chip strategy was applied to modify single tungsten atom oxide on a lead halide perovskite,which provides sensitive SERS quantification for various analytes,including rhodamine,tyrosine and cytosine.The single-atom site on a chip can enable quantitative linear SERS responses of rhodamine(10^(−6)-1 mmol L^(−1)),tyrosine(0.06-1 mmol L^(−1))and cytosine(0.2-45 mmol L^(−1)),respectively,which all achieve record-high enhancement factors among plasmonic-free semiconductors.The experimental test and theoretical simulation both reveal that the enhanced mechanism can be ascribed to the controllable single-atom site,which can not only trap photoinduced electrons from the perovskite substrate but also enhance the highly efficient and quantitative charge transfer to analytes.Furthermore,the label-free strategy of single-atom sites on a chip can be applied in a portable Raman platform to obtain a sensitivity similar to that on a benchtop instrument,which can be readily extended to various biomolecules for low-cost,widely demanded and more precise point-of-care testing or in-vitro detection.展开更多
Rational design of earth-abundant transition metal oxides catalysts is highly desirable for developing sustainable chemical processes.Herein,we demonstrate a prospective interstitial nitrogen engineering for fabricati...Rational design of earth-abundant transition metal oxides catalysts is highly desirable for developing sustainable chemical processes.Herein,we demonstrate a prospective interstitial nitrogen engineering for fabricating oxygen vacancies(OVs)-rich nitrogen-doped-Mn_(x)Co_(3-x)O_(4)(N-Mn_(x)Co_(3-x)O_(4))oxide catalyst,in which the ratio of OVs concentration of N-Mn_(x)Co_(3-x)O_(4)to Mn species is as high as 1:1,according to the characterizations of X-ray absorption(XAS)and X-ray photoelectron(XPS)spectroscopies.The promising strategy of interstitial nitrogen engineering through lattice distortion caused by the Jahn-Teller effect can significantly increase the amount of interstitial nitrogen.The resulting catalyst enables an additive-free aerobic dehydrogenation coupling of aromatic amine to afford azo compounds with>99%yield and>99%selectivity at 60☆.We observed the superb catalytic activity is promoted by the enhanced oxygen mobility in OVs,which were created by the interstitial nitrogen in the catalyst matrix.The presence of interstitial nitrogen in transition metal oxides in this study shows how the manipulation of catalyst matrix can increase the OV sites to promote aerobic oxidation reaction.展开更多
MXenes are promising supports for anchoring metal single atoms due to their versatile composition,well-defined nanostructures,and suitable conductivity.However,metal single atoms are usually coordinated with surface t...MXenes are promising supports for anchoring metal single atoms due to their versatile composition,well-defined nanostructures,and suitable conductivity.However,metal single atoms are usually coordinated with surface terminal groups(-O,-OH,-Cl,etc.)of MXenes via conventional wet-impregnation,resulting in limited electronic structure modification.Through a NiCl2 molten salt etching method,we observed that Ni single atoms could be in-situ doped in the lattice of MXenes analogue TiC_(0.5)N_(0.5) support(denoted as Ni1/TiC0.5N0.5),resulting in much larger charge transfer from Ni atoms to adjacent Ti atoms,and thus increasing the electronic density of these Ti atoms.When used for NO_(2) sensing,Ni_(1)/TiC_(0.5)N_(0.5) exhibited excellent response sensitivity(ultra-low limit of detection~10 ppb),selectivity,and good stability at room temperature.This study provides an effective strategy for producing MXenes analogue supported metal single atoms for potential application in gas sensing.展开更多
O_(x)idative couplings of aliphatic alkynes are crucial for the production of naturally occurring 1,3-diynes.Herein we report the novel approach for effective synthesis of unsaturated coordinated N doped copper oxides...O_(x)idative couplings of aliphatic alkynes are crucial for the production of naturally occurring 1,3-diynes.Herein we report the novel approach for effective synthesis of unsaturated coordinated N doped copper oxides(N-CuO_(x))catalyst,and uncover that N-CuO_(x) catalyst as an additive-free and cost-effective heterogeneous catalyst has highly catalytic performance for directly oxidative coupling of aliphatic alkynes.The key to achieve efficient oxidative coupling of aliphatic alkynes is the synergistic effect of N species and uncoordinated O/Cu species caused by N dopants,which undergoes the Langmuir–Hinshelwood reaction mechanism.The N-CuO_(x) catalyst displays~89.1%yield for hexadeca-7,9-diyne under mild conditions and stable reusability(5 cycles),showing significant advances compared with the traditionally copper oxides.These findings highlight the heteroatom dopants that provide a new methodology for designing efficient copper catalysts in synthesis of naturally occurring 1,3-diynes.展开更多
Transition metal phosphides(TMPs)/carbonaceous matrices have gradually attracted attention in the field of energy storage.In this study,we presented nickel phosphide(Ni2P)nanoparticles anchored to nitrogen-doped carbo...Transition metal phosphides(TMPs)/carbonaceous matrices have gradually attracted attention in the field of energy storage.In this study,we presented nickel phosphide(Ni2P)nanoparticles anchored to nitrogen-doped carbon porous spheres(Ni2P/NC)by using metal-organic framework-Ni as the template.The comprehensive encapsulation architecture provides closer contact among the Ni2P nanoparticles and greatly improves the structural integrity as well as the electronic conductivity,resulting in excellent lithium storage performance.The reversible specific capacity of 286.4 mA hg^-1 has been obtained even at a high current density of 3.0 Ag^-1 and 450.4 mA hg^-1 is obtained after 800 cycles at 0.5 Ag^-1.Furthermore,full batteries based on LiNi1/3Co1/3Mn1/3O2||Ni2P/NC exhibit both good rate capability and cycling life.This study provides a powerful and indepth insight on new advanced electrodes in high-performance energy storage devices.展开更多
文摘通过电解水制备氢气是实现“碳中和”目标的理想途径之一.因此,可在全p H条件下使用的氢析出(HER)催化剂的研发是近年来电催化领域的研究热点.原子级分散的催化剂,能够在保留铂族金属(PGM)固有活性的同时,降低催化剂中PGM的用量.虽然可以通过X射线吸收光谱(XAS)来表征原子分散的PGM电催化剂的配位环境,但目前对原子空间分布的控制仍然具有挑战.本文制备了钒掺杂钨青铜内通道氨配位的钌单原子催化剂(Ru/V-NHWO),用于全p H范围内的HER反应.采用X射线衍射(XRD)、高角环形暗场扫描透射电镜(HAADF-STEM)、X射线光电子能谱(XPS)和原位X射线吸收光谱(XAS)等进行表征,研究了钌单原子与V-NHWO载体的结合方式以及构效关系,并采用密度泛函理论(DFT)计算探索了催化剂中诸多位点的活性贡献.在1 mol/LKOH, 0.5 mol/L H_(2)SO_(4)和1 mol/L磷酸盐缓冲溶液中,其在10 m Acm^(-2)下的过电位分别为28.0, 29.6和40.6 m V.同时,在过电位100 m V时,质量活性分别达到3930, 1941和602.8 m Amg^(-1)Ru,数倍于同等条件下的商业铂碳.XRD结果表明,钌的引入可以确保催化剂在氩气条件下热解后仍保持六方钨铵青铜晶相,证明钌与钨铵青铜六方晶体通道内氨物种,即“通道氨”的结合.HAADF-STEM结果表明,钌原子与NHWO间存在强烈相互作用,有助于提升HER性能.XPS和XAS结果表明, W5+信号出现在引入钌后,峰位置的结合能增加且峰面积降低,说明钌与通道氨之间存在相互作用.N的XPS结果表明,钌的引入导致了金属氨键的形成.XAS结果表明, Ru/V-NHWO/CC中钌单原子和钌团簇共存,钌单原子与通道氨配位,并且钒的引入会诱发V-NHWO中金属键长缩短,这表明催化剂的金属性得到了提升,有利于改善其导电性.采用DFT计算进一步研究了HER活性的来源.相比于V-NHWO载体和钌团簇修饰的V-NHWO,以单原子形式结合的钌具有更低的水解离能垒,该能垒在氨桥接的钌双原子垂直插入、钒掺杂和多通道插入等多种因素作用下进一步降低.同时,氢中间体结合能得到了相应的优化而趋近于0 e V.此外,差分电荷密度模拟结果表明,氢中间体结合后, V-NHWO对于钌单原子存在明显的供电子行为,有利于HER动力学过程.综上,本工作报道了金属载体对于高分散金属原子空间分布调控的重要作用,可为设计和构筑可应用于诸多能源转换过程的新型原子级分散催化剂提供参考.
基金supported bythe Natural Scientific Foundation of China(Grants 21878001,22078002,21776001,21875001,21978002,21808002,22008001,and U1710114).
文摘Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conversion.However,high-performance TiO_(2)-based electrocatalysts for HER are quite limited,and the cat alytic active centers still remain elusive.Herein,a simple strategy is demonstrated for the synthesis of TiO_(2)-carbon composite(TiO_(2)/C)with high HER performance and stability.The remarkable HER performance of TiO_(2)/C can be ascribed to the doping of carbon atoms,which leads to stronger hybridization of Ti 3d and O 2p orbitals,thus substantially improving the electrocatalytic efficiency.This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electro catalysts with high catalytic activity and stability at high current density for HER.
基金This work was jointly supported by the National Key Research and Development Program of China(Nos.2017YFA0206500 and 2018YFA0209103)the National Natural Science Foundation of China(Nos.21832003,21773111,51571110,and 21573107)the Fundamental Research Funds for the Central Universities(No.020514380126).
文摘As a choke point in water electrolysis,the oxygen evolution reaction(OER)suffers from the severe electrode polarization and large overpotential.Herein,the porous hierarchical hetero-(Nis Fe)FeN/Ni catalysts are in situ constructed for the eficient electrocatalytic OER.X-ray absorption fine structure characterizations reveal the strong Ni-Fe bimetallic interaction in(Niz Fex)FeN/Ni.Theoretical study indicates the heterojunction and bimetallic interaction decrease the free-energy change for the rate-limiting step of the OER and the overpotential thereof.In addition,the high conductivity and porous hierarchical morphology favor the electron transfer,electrolyte access and O2 release.Consequently,the optimized catalyst achieves a low overpotential of 223 mV at 10 mA.cm^-2,a small Tafel slope of 68 mV:dec^-1,and a high stability.The excellent performance of the optimized catalyst is also demonstrated by the overall water electrolysis with a low working voltage and high Faradaic efficiency.Moreover,the correlation between the structure and performance is well established by the experimental characterizations and theoretical calculations,which confirms the origin of the OER activity from the surface metal oxyhydroxide in situ generated upon applying the current.This study suggests a promising approach to the advanced OER electrocatalysts for practical applications by constructing the porous hierarchical metal-compound/metal heterojunctions.
基金supported by the Ministry of Science and Technology of China (2017YFA0204502)the National Natural Science Foundation of China (21873105)
文摘The structural flexibility of hybrid perovskite materials allows for phase transition and consequently thermochromic properties.Here we investigate the thermochromic performance in a series of copper-based layered perovskites with organic cations having different alky chain lengths. Their transition temperature is found to be dependent on the organic cations due to molecular motion and hydrogen bond interaction, providing possibilities to prepare thermochromic semiconductors near room temperature for smart window applications.
基金We thank the National Key R&D Program of China(Nos.2018YFA0703503 and 2018YFA0208504)the National Natural Science Foundation of China(No.21932006)the Youth Innovation Promotion Association of CAS(No.2017049)for financial support.
文摘Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,including a H_(2)O_(2)molecule dissociated on the metal single site to form the(metal_(1)-N_(x))=O active site,and followed by the dissociation of another H_(2)O_(2)on the other side of metal atom to form O=(metal_(1)-N_(x))=O intermediate center,which is active for the adsorption of benzene molecule via the formation of a C-O bond to form phenol.In this manuscript,we report a Cu SAC with nitrogen and oxygen dual-coordination(Cu1-N3O1 moiety)that doesn’t need the first H_(2)O_(2)activation process,as verified by both experimental and density function theory(DFT)calculations results.Compared with the counterpart nitrogen-coordinated Cu SAC(denoted as Cu1/NC),Cu SAC with nitrogen and oxygen dual-coordination(denoted as Cu1/NOC)exhibits 2.5 times higher turnover frequency(TOF)and 1.6 times higher utilization efficiency of H_(2)O_(2).Particularly,the coordination number(CN)of Cu atom in Cu1/NOC maintains four even after H_(2)O_(2)treatment and reaction.Combining DFT calculations,the dynamic evolution of single atomic Cu with nitrogen and oxygen dualcoordination in hydroxylation of benzene is proposed.These findings provide an efficient route to improve the catalytic performance through regulating the coordination environments of SACs and demonstrate a new reaction mechanism in hydroxylation of benzene to phenol reaction.
基金This work was jointly supported by the National Key Research and Development Program of China (Nos. 2017YFA0206500 and 2018YFA0209103)the National Natural Science Foundation of China (Nos. 52071174, 21832003, 21773111, and 21972061)+1 种基金the Fundamental Research Funds for the Central Universities (No. 020514380126)The numerical calculations have been done on the computing facilities in the High Performance Computing Center (HPCC) of Nanjing University. We thank the staff of the BL14W1 beamline at Shanghai Synchrotron Radiation Facility for assistance with the X-ray absorption measurements.
文摘The investigation of earth-abundant electrocatalysts for efficient water electrolysis is of central importance in renewable energy system, which is currently impeded by the large overpotential of oxygen evolution reaction (OER). NiFe sulfides show promising OER activity but are troubled by their low intrinsic conductivities. Herein, we demonstrate the construction of the porous core-shell heterojunctions of FeNi3@(Fe,Ni)S_(2) with tunable shell thickness via the reduction of hierarchical NiFe(OH)x nanosheets followed by a partial sulfidization. The conductive FeNi3 core provides the highway for electron transport, and the (Fe,Ni)S_(2) shell offers the exposed surface for in situ generation of S-doped NiFe-oxyhydroxides with high intrinsic OER activity, which is supported by the combined experimental and theoretical studies. In addition, the porous hierarchical morphology favors the electrolyte access and O_(2) liberation. Consequently, the optimized catalyst achieves an excellent OER performance with a low overpotential of 288 mV at 100 mA·cm^(−2), a small Tafel slope of 48 mV·dec^(−1), and a high OER durability for at least 1,200 h at 200 mA·cm^(−2). This study provides an effective way to explore the advanced earth-abundant OER electrocatalysts by constructing the heterojunctions between metal and corresponding metal-compounds via the convenient post treatment, such as nitridation and sulfidization.
基金supported by the Natural Science Foundation of Beijing Municipality(Z180014)。
文摘Surface enhanced Raman scattering(SERS)is a rapid and nondestructive technique that is capable of detecting and identifying chemical or biological compounds.Sensitive SERS quantification is vital for practical applications,particularly for portable detection of biomolecules such as amino acids and nucleotides.However,few approaches can achieve sensitive and quantitative Raman detection of these most fundamental components in biology.Herein,a noblemetal-free single-atom site on a chip strategy was applied to modify single tungsten atom oxide on a lead halide perovskite,which provides sensitive SERS quantification for various analytes,including rhodamine,tyrosine and cytosine.The single-atom site on a chip can enable quantitative linear SERS responses of rhodamine(10^(−6)-1 mmol L^(−1)),tyrosine(0.06-1 mmol L^(−1))and cytosine(0.2-45 mmol L^(−1)),respectively,which all achieve record-high enhancement factors among plasmonic-free semiconductors.The experimental test and theoretical simulation both reveal that the enhanced mechanism can be ascribed to the controllable single-atom site,which can not only trap photoinduced electrons from the perovskite substrate but also enhance the highly efficient and quantitative charge transfer to analytes.Furthermore,the label-free strategy of single-atom sites on a chip can be applied in a portable Raman platform to obtain a sensitivity similar to that on a benchtop instrument,which can be readily extended to various biomolecules for low-cost,widely demanded and more precise point-of-care testing or in-vitro detection.
基金supported by the Anhui Provincial Natural Science Foundation of China(2008085M47)“Key Program for International S&T Cooperation Projects of China”(No.2017YFE0124300)Anhui Provincial Science Fund for Excellent Young Scholars(gxyqZD2018034).
文摘Rational design of earth-abundant transition metal oxides catalysts is highly desirable for developing sustainable chemical processes.Herein,we demonstrate a prospective interstitial nitrogen engineering for fabricating oxygen vacancies(OVs)-rich nitrogen-doped-Mn_(x)Co_(3-x)O_(4)(N-Mn_(x)Co_(3-x)O_(4))oxide catalyst,in which the ratio of OVs concentration of N-Mn_(x)Co_(3-x)O_(4)to Mn species is as high as 1:1,according to the characterizations of X-ray absorption(XAS)and X-ray photoelectron(XPS)spectroscopies.The promising strategy of interstitial nitrogen engineering through lattice distortion caused by the Jahn-Teller effect can significantly increase the amount of interstitial nitrogen.The resulting catalyst enables an additive-free aerobic dehydrogenation coupling of aromatic amine to afford azo compounds with>99%yield and>99%selectivity at 60☆.We observed the superb catalytic activity is promoted by the enhanced oxygen mobility in OVs,which were created by the interstitial nitrogen in the catalyst matrix.The presence of interstitial nitrogen in transition metal oxides in this study shows how the manipulation of catalyst matrix can increase the OV sites to promote aerobic oxidation reaction.
基金National Key R&D Program of China(No.2018YFA0208504)the National Natural Science Foundation of China(Nos.21932006 and 92161112)+1 种基金the National Science Basic Research Program of Shaanxi(Nos.S2020-JC-WT-0001 and 2021JCW-20)the Youth Innovation Promotion Association of CAS(No.Y2017049)for financial support.
文摘MXenes are promising supports for anchoring metal single atoms due to their versatile composition,well-defined nanostructures,and suitable conductivity.However,metal single atoms are usually coordinated with surface terminal groups(-O,-OH,-Cl,etc.)of MXenes via conventional wet-impregnation,resulting in limited electronic structure modification.Through a NiCl2 molten salt etching method,we observed that Ni single atoms could be in-situ doped in the lattice of MXenes analogue TiC_(0.5)N_(0.5) support(denoted as Ni1/TiC0.5N0.5),resulting in much larger charge transfer from Ni atoms to adjacent Ti atoms,and thus increasing the electronic density of these Ti atoms.When used for NO_(2) sensing,Ni_(1)/TiC_(0.5)N_(0.5) exhibited excellent response sensitivity(ultra-low limit of detection~10 ppb),selectivity,and good stability at room temperature.This study provides an effective strategy for producing MXenes analogue supported metal single atoms for potential application in gas sensing.
基金supported by the“Key Program for International S&T Cooperation Projects of China”(No.2017YFE0124300)Anhui Provincial Natural Science Foundation of China(No.2008085M47)+1 种基金Key Projects of the Department of Education of Anhui Province of China(No.RZ2000003450)The authors thank the beamline BL14W1 at Shanghai Synchrotron Radiation Facility(SSRF).
文摘O_(x)idative couplings of aliphatic alkynes are crucial for the production of naturally occurring 1,3-diynes.Herein we report the novel approach for effective synthesis of unsaturated coordinated N doped copper oxides(N-CuO_(x))catalyst,and uncover that N-CuO_(x) catalyst as an additive-free and cost-effective heterogeneous catalyst has highly catalytic performance for directly oxidative coupling of aliphatic alkynes.The key to achieve efficient oxidative coupling of aliphatic alkynes is the synergistic effect of N species and uncoordinated O/Cu species caused by N dopants,which undergoes the Langmuir–Hinshelwood reaction mechanism.The N-CuO_(x) catalyst displays~89.1%yield for hexadeca-7,9-diyne under mild conditions and stable reusability(5 cycles),showing significant advances compared with the traditionally copper oxides.These findings highlight the heteroatom dopants that provide a new methodology for designing efficient copper catalysts in synthesis of naturally occurring 1,3-diynes.
基金partly supported by the National Natural Science Foundation of China(11705015 and U1832147)the Foundation of Jiangsu Science and Technology Department(BA2016041)the Science and Technology Plan Project of Suzhou(SYG201738 and SZS201710)。
文摘Transition metal phosphides(TMPs)/carbonaceous matrices have gradually attracted attention in the field of energy storage.In this study,we presented nickel phosphide(Ni2P)nanoparticles anchored to nitrogen-doped carbon porous spheres(Ni2P/NC)by using metal-organic framework-Ni as the template.The comprehensive encapsulation architecture provides closer contact among the Ni2P nanoparticles and greatly improves the structural integrity as well as the electronic conductivity,resulting in excellent lithium storage performance.The reversible specific capacity of 286.4 mA hg^-1 has been obtained even at a high current density of 3.0 Ag^-1 and 450.4 mA hg^-1 is obtained after 800 cycles at 0.5 Ag^-1.Furthermore,full batteries based on LiNi1/3Co1/3Mn1/3O2||Ni2P/NC exhibit both good rate capability and cycling life.This study provides a powerful and indepth insight on new advanced electrodes in high-performance energy storage devices.
